The Practical Use of the DMM Model for Life Estimation of HVDC Cables Subjected to Qualification Load Cycles

A procedure for life and reliability estimation of full size HVDC cables under the electro-thermal transients caused by load cycles was successfully set up and applied to qualification load cycles prescribed by Cigrè TB 496 and 852. However, a gap in the procedure is that only the phenomenological electro-thermal IPM-Arrhenius life model was used so far, while no physical life model was ever employed. The estimation of phenomenological life model parameters requires accelerated life test data fitting without an in-depth understanding of aging processes. Physical life models are appealing as they take degradation due to local micro-defects as the main source of aging, and their parameters in principle could be derived from short-term chemical-physical measurements on small dielectric specimens. The paper fills this gap by using the physical DMM life model for life estimation of HVDC cables under the electro-thermal transients involved by qualification test load cycles. The practical difficulties in using physical models in general, and the DMM in particular, are analyzed and assessed resorting to an application relevant to prequalification load cycles according to TB 852.